overhaul engine top

Hi,

I have a GPz750 engine, the engine is running fine, but I shall replace the top gasget and when I do these
I want to rebuild the engine as the same time.

1. Honing cylinders
2. replace the piston rings
3. More I should do with the cylinders / pistons?

But what about the top, I have been informed I should replace the sealigs for the valves,
but should I do more? replace the piston springs? do someting with the valve to make them good as new and 100% air tight ??
more ?

Thank you for sharing your acknowledge for overhaul the engine on the top side.

Why would you do all that work if it runs fine, we have a saying in the UK, if it ain't broke don't fix it.

kevski wrote: Why would you do all that work if it runs fine, we have a saying in the UK, if it ain't broke don't fix it.

We have the same saying here in the US, for the same reason.

I don't understand the the logic in taking apart an engine that is running fine. Since it runs fine just ride and enjoy it. If it's a matter of curiosity I suggest it makes more sense to buy an inexpensive engine that does not run and take it apart to fix it. Ed

650ed wrote:

kevski wrote: Why would you do all that work if it runs fine, we have a saying in the UK, if it ain't broke don't fix it.

We have the same saying here in the US, for the same reason.

I don't understand the the logic in taking apart an engine that is running fine. Since it runs fine just ride and enjoy it. If it's a matter of curiosity I suggest it makes more sense to buy an inexpensive engine that does not run and take it apart to fix it. Ed

Do you also share the K.I.S.S analogy of Keep It Simple Stupid.

Yes, we do. Although I sometimes forget to do it. :laugh: Ed

hehe and I will save money also

The engine using oil, but I can off course add in between.

It was more that I want to have a hobby and like to learn and like to fix the whole bike to be 100%, but off course I can start with the cosmetic of the engine first. and then overhaul other part of the bike as the brake caliper etc.. .

Let me think on it

I forgot one thing, I need to replace the head gasket en the o-rings on top of the block, it`s no problem just replacing these?
The gaskett under the block will not start leaking or something?

That's the trouble many times you will break the base gasket loose removing the head and if you don't replace it it will leak and then you need at a min rings and a hone..... and since you have the head off seals and a lap or maybe grinding and hopefully the guides are good..... one thing leads to another.

I don^t want todo thes two times, so I think I will go for the plan...
honing cylinders, replace rings, replace seals valves, but what is lap, grindings, guides?

lap = to make the valves 100& air tight ?
grinding= if the surface on block and top is not 100% align, so you will not get it 100% tight when you replace the gasket?
guiding = the bolts who fasting the top?

gordone wrote: I don^t want todo thes two times, so I think I will go for the plan...
honing cylinders, replace rings, replace seals valves, but what is lap, grindings, guides?

lap = to make the valves 100& air tight ?
grinding= if the surface on block and top is not 100% align, so you will not get it 100% tight when you replace the gasket?
guiding = the bolts who fasting the top?

All valve related
Make sure valve guides are snug to the valve stems ( No extra play )
Lap and or grind valves and or valve seats to insure perfect seating and seal to valve seats.
Block ( cylinder ) and head are almost never ground flat during a rebuild
Read factory service manual until all needed work is clear to you
Dave

Thank you for all information !

I have one more questions right now, what is the chance the base gasket under the block will start leak If I only replace the top gasket and the o-rings (oil channel) in the top?

gordone wrote: Thank you for all information !

I have one more questions right now, what is the chance the base gasket under the block will start leak If I only replace the top gasket and the o-rings (oil channel) in the top?

Chance of a leak at base gasket is 50/50 based on your ability to not disturb seal and fit between cases and block.
Dave